A dehumidifier is essentially a \"refrigerator with an open door.\" The humid ai

Question

A dehumidifier is essentially a "refrigerator with an open door." The humid air IS pulled in by a fan and guided to a cold coil whose temperature is less than the dew point, and some of the air's water condenses. After this water is extracted, the air is warmed back to its original temperature and sent into the room. In a well-designed de-humidifier, the heat is exchanged between the incoming and outgoing air. Thus the heat that is removed by the refrigerator coil mostly comes from the condensation of water vapor to liquid. Estimate how much water is removed in 1.0 h by an ideal dehumidifier, if the temperature of the room is 25 degree C, the water condenses at 80 degree C, and the dehumidifier does work at the rate of 650 W of electrical power.

Explanation / Answer

Total work done in 1 hour by 650 W of electric power = 650*3600

                                                                                      = 2340000 J

Heat involved = m* s* t

Total water removed in 1 hour = (650*3600)/(2*17*4186)

                                                 = about 17 kg of water from air

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